Abacus attachment for school-slates



(No Model.)

H. STEWART.

. AB AOUS ATTAGHMENT POR'SGHOOL SLATES. No.271,749., Patented Peb.6 ,1883:

' UNiT D- STATES PATENT- FFI HENRY STEWART, ERIE, PENNSYLVANIA.

ABA CUS ATTACHMENT FOR S-CHOOL-SLATES.

SPECIFICATION forming part of Letters Patent No. 271,749, dated February 6, 1883.

' Application filedNovemher 15, 1882. (No model.)

To all whom it may concern:

Be itknown that I, HENRY STEWART, of Erie, in the county of Erie and State of Pennsylvania, have invented certain new and useful Improvements in Abacus Attachments for School-Slates; and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the artto which it appertains to make and use the same, reference being bad to the accompanying drawings, and to the letters of reference marked thereon, which form a partof this specification,

My invention is for an attachment to common school-slates, which I term Abacus Attachment for Slates; and it has for its object to assist in imparting to young pupils in schools the elementary principles of arithmetic.

Asis well known, an abacus is a calculating-machine used in school-rooms to facilitate arithmetical computation, or, in other words, a machine for expressing the properties andrelations of numbers with objects. This method is often used in common schools to aid the primary in grasping the first principles of;

desired.

Referring to the drawings, Figure 1 is a perspective view of my improved attachment as secured to a slate; and Fig. 2 is a perspective view, showing it detached.

AandA' constitute the frame ofthe abacus attachment, made ofany kind of wood or any material, in one or more parts, into any desired shape, either somewhat in the form of an in-, verted bow, as shown, or otherwise, and of length either of the width of the slate or of its length. Extending between the two arms or shorter sides, a and a, of theframe is a wire or wires, 12, upon which are strung a number of balls or, counters, c, which are'adapted to slide back and forth on the wire. The object of the balls so strung, as before mentioned, is to help the primary to add, subtract, divide, or multiply. These balls areunnumbered,and have no characters whatever "upon them, they being plain, as by the use of balls or counters having numerals or representations upon them the. scholar confuses the character on the balls with the number of balls--thatis, between the quantity desired toexpress a number with the symbol which stands for that number. Thus in calculations the presence of characters on the balls is confusing when bya mental effort they have to be disregarded. Children also may acquire thetrick of reading the number on the last ball of a series, and thus give a correct answer without at all appreciating the quantity expressed by the numerical character they make use of in their reply, which would not be the case if they could arrive at their conclusions only by counting on unnumbered balls. By these means it will be seen that the use of counters without characters on them is a great improvement in object-teachbroadly claim; but it is thought that the idea of an abacus attachment to a school-slate having unnumbered counters is new.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-

1. As an attachment to a school-slate, an

abacus or calculating-m achine, the frame A A,

having strung upon a wire therein one or more series of unnumbered counters, in-combinatiou with the fastening devices whereby the abacus may be fastened to the slate, substantially as described.

2. An abacus or calculating device composed of the frame A A, the wire or wires 12,

substantially as specified.

having strung upon them the unnumbered In testimony that Iclaim the foregoing as counters c.'and thefastening devices B B,

my own I affix'my signature in presence of two 1 o witnesses. 3. 'The combination, with a school-slate, of

5 an abacus or calculating device, constructed HENRY STEWART as described, having the devices B B for attachment to said slate, substantially as and for the purpose described.

Witnesses; M CLAR OLDS, S. M. BRAINERD. 

